ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 146 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-am335x.c b/drivers/usb/phy/phy-am335x.c
new file mode 100644
index 000000000..ca9353dad
--- /dev/null
+++ b/drivers/usb/phy/phy-am335x.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+#include <linux/usb/otg.h>
+#include <linux/usb/usb_phy_generic.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/usb/of.h>
+
+#include "phy-am335x-control.h"
+#include "phy-generic.h"
+
+struct am335x_phy {
+	struct usb_phy_generic usb_phy_gen;
+	struct phy_control *phy_ctrl;
+	int id;
+	enum usb_dr_mode dr_mode;
+};
+
+static int am335x_init(struct usb_phy *phy)
+{
+	struct am335x_phy *am_phy = dev_get_drvdata(phy->dev);
+
+	phy_ctrl_power(am_phy->phy_ctrl, am_phy->id, am_phy->dr_mode, true);
+	return 0;
+}
+
+static void am335x_shutdown(struct usb_phy *phy)
+{
+	struct am335x_phy *am_phy = dev_get_drvdata(phy->dev);
+
+	phy_ctrl_power(am_phy->phy_ctrl, am_phy->id, am_phy->dr_mode, false);
+}
+
+static int am335x_phy_probe(struct platform_device *pdev)
+{
+	struct am335x_phy *am_phy;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	am_phy = devm_kzalloc(dev, sizeof(*am_phy), GFP_KERNEL);
+	if (!am_phy)
+		return -ENOMEM;
+
+	am_phy->phy_ctrl = am335x_get_phy_control(dev);
+	if (!am_phy->phy_ctrl)
+		return -EPROBE_DEFER;
+
+	am_phy->id = of_alias_get_id(pdev->dev.of_node, "phy");
+	if (am_phy->id < 0) {
+		dev_err(&pdev->dev, "Missing PHY id: %d\n", am_phy->id);
+		return am_phy->id;
+	}
+
+	am_phy->dr_mode = of_usb_get_dr_mode_by_phy(pdev->dev.of_node, -1);
+
+	ret = usb_phy_gen_create_phy(dev, &am_phy->usb_phy_gen);
+	if (ret)
+		return ret;
+
+	am_phy->usb_phy_gen.phy.init = am335x_init;
+	am_phy->usb_phy_gen.phy.shutdown = am335x_shutdown;
+
+	platform_set_drvdata(pdev, am_phy);
+	device_init_wakeup(dev, true);
+
+	/*
+	 * If we leave PHY wakeup enabled then AM33XX wakes up
+	 * immediately from DS0. To avoid this we mark dev->power.can_wakeup
+	 * to false. The same is checked in suspend routine to decide
+	 * on whether to enable PHY wakeup or not.
+	 * PHY wakeup works fine in standby mode, there by allowing us to
+	 * handle remote wakeup, wakeup on disconnect and connect.
+	 */
+
+	device_set_wakeup_enable(dev, false);
+	phy_ctrl_power(am_phy->phy_ctrl, am_phy->id, am_phy->dr_mode, false);
+
+	return usb_add_phy_dev(&am_phy->usb_phy_gen.phy);
+}
+
+static void am335x_phy_remove(struct platform_device *pdev)
+{
+	struct am335x_phy *am_phy = platform_get_drvdata(pdev);
+
+	usb_remove_phy(&am_phy->usb_phy_gen.phy);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int am335x_phy_suspend(struct device *dev)
+{
+	struct am335x_phy *am_phy = dev_get_drvdata(dev);
+
+	/*
+	 * Enable phy wakeup only if dev->power.can_wakeup is true.
+	 * Make sure to enable wakeup to support remote wakeup	in
+	 * standby mode ( same is not supported in OFF(DS0) mode).
+	 * Enable it by doing
+	 * echo enabled > /sys/bus/platform/devices/<usb-phy-id>/power/wakeup
+	 */
+
+	if (device_may_wakeup(dev))
+		phy_ctrl_wkup(am_phy->phy_ctrl, am_phy->id, true);
+
+	phy_ctrl_power(am_phy->phy_ctrl, am_phy->id, am_phy->dr_mode, false);
+
+	return 0;
+}
+
+static int am335x_phy_resume(struct device *dev)
+{
+	struct am335x_phy	*am_phy = dev_get_drvdata(dev);
+
+	phy_ctrl_power(am_phy->phy_ctrl, am_phy->id, am_phy->dr_mode, true);
+
+	if (device_may_wakeup(dev))
+		phy_ctrl_wkup(am_phy->phy_ctrl, am_phy->id, false);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(am335x_pm_ops, am335x_phy_suspend, am335x_phy_resume);
+
+static const struct of_device_id am335x_phy_ids[] = {
+	{ .compatible = "ti,am335x-usb-phy" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, am335x_phy_ids);
+
+static struct platform_driver am335x_phy_driver = {
+	.probe          = am335x_phy_probe,
+	.remove         = am335x_phy_remove,
+	.driver         = {
+		.name   = "am335x-phy-driver",
+		.pm = &am335x_pm_ops,
+		.of_match_table = am335x_phy_ids,
+	},
+};
+
+module_platform_driver(am335x_phy_driver);
+MODULE_DESCRIPTION("AM335x USB PHY Driver");
+MODULE_LICENSE("GPL v2");